Onboard CTI systems are known, as may be seen by reference to U.S. Pat. Nos. 4,640,331; 4,498,515, 4,898,216 and 4,917,163 which are incorporated herein by reference. Further, it is known to provide apparatus for transmitting the CTI system air from a nonrotating portion of the CTI system air circuit to a wheel hub rotatably mounted on the spindle of the drive axle, as may be seen by reference to U.S. Pat. Nos. 2,976,906; 3,362,452; 4,418,737; 4,730,656 and 4,804,027 which disclose such apparatus in detail and which are incorporated herein by reference.
The prior art apparatus of each of the above patents has certain disadvantages which are overcome by the apparatus of this invention. For example, the apparatus of this invention: requires little or not modification of a standard drive axle and is therefore ideal for retrofit applications; does not require the drilling of long passages in hardened steel components such as axle spindles or sleeves; does not require nonstandard or special wheel bearing components; positions dynamic air seals for the CTI system between the inboard and outboard bearings of each drive axle wheel hub where they are protected from dirt and grime, and are readily lubricated by the drive axle lubricating oil; avoids encroachment into the sometimes hot and always limited space for the wheel brakes; provides the CTI system with air passages of adequate flow area while maintaining the total volume thereof rather low.